Olefin separation process

ABSTRACT

1. A PROCESS FOR THE SEPARATION OF A MONO-OLEFIN FROM A MIXTURE OF PARFFINIC, OLEFINIC OR AROMATIC COMPOUNDS WHICH COMPRISES CONTACTING SAID MIXTURE WITH A THIOL RESIN AND REACTING THE OLEFIN WITH THE RESIN, HEATING THE RESULTING REACTION PRODUCT TO A TEMPERATURE SUFFICIENT TO DECOMPOSE THE SAME TO OLEFIN AND THIOL RESIN, AND RECOVERRIN THE THUS LIBERATED OLEFIN.

United States Patent 3,839,482 OLEFIN SEPARATION PROCESS Herman S.Bloch, Skokie, Ill., assignor to Universal Oil Products Company, DesPlaines, Ill. No Drawing. Filed Dec. 21, 1972, Ser. No. 317,328 Int. Cl.C07c 11/00 US. Cl. 260-677 A 9 Claims ABSTRACT OF THE DISCLOSURE Aprocess for the separation of olefins from a paraffinic, olefinic andaromatic mixture by passage of said mixture over a thiol resin whereby aseparation of the desired olefin is accomplished by formation of athio-ether.

This invention relates to a process for the separation of an olefin froma mixture of paraflinic, olefinic and aromatic compounds. Morespecifically, this invention relates to a process for the separation ofan olefin from a mixture of paraffinic, olefinic and aromatic compoundsby contacting said mixture with a thiol-containing resin and recoveringthe resultant olefin.

It has been shown in the prior art that olefins may be extracted from aparafiinic, olefinic and aromatic mixture by fractional extraction usinga heavy metal salt cation exchange resin from the Groups IB and HE ofthe Periodic Table or by utilization of complex forming reagents such asurea and thiourea in a fractional extraction process to separatebranched and straight chained organic compounds.

In contradistinction to the prior art, it has now been discovered that athiol resin may be utilized in the separation of an olefin from amixture of paraifinic, olefinic and aromatic compounds by contactingsaid mixture with the resin thereby forming thio-ethers while notimpeding the passage of non-olefinic components of the mixture throughthe separation zone. The thiol resin can also be utilized in theseparation of a-olefins from internal olefins by contacting a mixture ofolefins with a thiol resin thereby forming thio-ethers with thea-olefins While not impeding the internal olefin passage over the resinthrough the separation zone. The thiol resin bed can be regenerated bythe addition of heat to reform the olefin and the thiol resin therebyenabling the manufacturer of the olefins to lower the operational costsas a result of the elimination of treating any cationic resin withregeneration reagents or the purchase of new separation chemicals asurea or thiourea. The reduction in the manufacturing cost Will enablethe manufacturer to lower the price of the olefins thereby reducing theconsumers cost in the many ways in which olefins are utilized.

The desired products of this separation process, namely, the olefins,are utilized in the chemical industry in many ways. For example, some ofthe ways in which the olefins are utilized in the chemical industryinclude the use of ethylene as a coloring agent in fruits and blanchingof vegetables, to increase the growth rate of seedlings, in welding andcutting metals, in medicine as an anesthetic, or the use of octenes asan anti-knock agent for gasoline, as a starting material for thepreparation of diolefins, alcohols and aldehydes and the use of pentenesin the synthesis of organic flavors, perfumes, medicines, dyes andresins.

It is therefore an object of this invention to provide a process for thepreparation of an olefin from a mixture of parafiinic, olefinic andaromatic compounds.

A further object of this invention is to provide a process for theseparation of an olefin utilizing a thiol resin which will permit therecovery of the desired olefinic compound in a more expedient manner.

In one aspect an embodiment of this invention resides ice in a processfor the separation of an olefin from a mixture of parafiinic, olefinicor aromatic compounds which comprises contacting said mixture with athiol resin at reaction conditions whereby the olefins are converted tothio-ethers and retained thereby while the non-olefinic compounds passthrough said resin, and recovering the resultant olefin.

A specific embodiment of this invention resides in a process forseparating butene-2 from a mixture containing butene-2, propane andbutane which comprises contacting said mixture with a vinylthiophenol-divinyl-benzene-styrene copolymer whereby the butene-Z formsa thio-ether upon the resin while the other components of the mixture,propane and butane pass over the said resin. The resin is purged withdecane to insure an absence of all non-olefinic compounds except decanein association with the thio-ether. The thio-ether is heated whichregenerates the butene-Z and some butene-l and the vinylthiophenol-divinylbenzene-styrene copolymer. The butenes are separatedfrom any decane present by means of distillation.

Another specific embodiment of this invention relates to a process forthe separation of pentene-l from a mixture which consists of pentene-l,pentene-2, heptene-Z and pentane which comprises contacting athio-methacrylic acid-divinylbenzene-methyl methacrylate copolymer ingranular form with said mixture at a liquid hourly space velocityregulated so as to provide that pentene-l will form a thio-ether uponthe thiol resin and is therefore retained while the other paraifinic andolefinic compounds, namely, pentene-2, heptene-2 and pentane, pass overthe thiol resin. The resin is purged with nonane to insure the removalof the unreacted feed components. The thio-ether is heated, whichliberates a mixture of pentene- 2 and pentene-l and the thio-methacrylicacid-divinylbenzene-methyl methacrylable copolymer. The n-pentenes aresubsequently purified from any remaining nonane by distillation.

Other objects and embodiments Will be found in the following furtherdetailed description of the present invention.

As herein set forth the present invention is concerned with a processfor separating an olefin from a mixture of parafiinic, olefinic andaromatic compounds or separating an a-olefin from internal olefins byutilizing a thiol resin. The separation is effected under reactionconditions which include a temperature in the range of from about 25 C.to about 150 C. and a pressure in the range of from about atmospheric toabout atmospheres. When superatmospheric pressures are to be employedsaid pressure may be generated autogenously or may be afforded by theintroduction of a substantially inert gas such as nitrogen, helium orargon into the separation zone, the particular pressure which is usedbeing that which is necessary to maintain a predetermined liquid phaselevel throughout the separation process. Another variable present is theliquid hourly space velocity which is defined as the volume of chargestock entered per hour to the separation zone per volume of thiol resinwithin the separation zone. The liquid hourly space velocity controlsthe retention time of the mixture through the thiol resin and isgenerally in the range of about 0.1 to about 25, being maintained at arate determined by the relative rates of forming the thio-ethers amongthe various components of the original mixture, as well as thetemperature.

Examples of suitable olefins that may be obtained from such a processwould include but are not limited to ethylene, propylene, butene-l,butene-2, isobutene, pentene-l, pentene-Z, Z-methylbutene-l,2-methylbutene-2, hexene- 1, 3-methylpentene-1, 2-methylpentene-2,heptene-2, 2- methylhexene-Z, 3-methylhexene-2, octene-3, octene-2, 3-

methylheptene-l, 2-methylheptene-2, nonene-2, 3-methyloctene-2,decene-Z, decene-3, 3,4-dimethyloctene-2, 4- ethyloctene-Z, undecene-3,undecene-4, 4-methyldecene-2, 4,5-dimethylnonene-2, dodecene-3,tridecene-2, tetradecene-3, pentadecene-S, heptene-l, octene-l,nonene-l, decene-l, undecene-l, dodecene-l, tridecene-l, tetradecene-l,pentadecene-l, etc.

Suitable mixtures utilized in thi separation process include any mixtureof parafiinic, olefinic or aromatic compounds. Some specific examples ofthe mixtures which may be involved include, in particular, butene-Z,propane, methane, ethane and butane; pentene-Z, pentane, heptane, hexaneand benzene; pentene-l, pentene-Z and heptene-Z; heptene-l, nonane,decane, cumene, toluene and p-xylene; decene-4, p-xylene, m-xylene,pseudocumene and hexamethylbenzene; nonene-l, nonane, heptane, decaneand undecane; ethylene, propane, methane and ethane; pentene-Z, pentane,butane and benzene; pentene- 1, pentene-2, heptene-Z and nonene-3;octene-l, octene-Z, octene-3 and pseudocumene; nonene-4, ethylbenzene,nbutylbenzene, p-xylene and toluene; undecene-S, undecane, tetradecane,o-xylene, m-xylene, p-xylene and cumene; decene-l,1,2,4,5,6-pentamethylbenzene, 1,4-diethylbenzene, 1,6-di-n-butylbenzeneand sec-butylbenzene; pentadecene-3, nonylbenzene, decylbenzene,hexamethylbenzene, and 1,2,3,5,6-pentamethylbenzene; tetradecene-l,undecene-2, tridecene-Z, decene-3, heptene-3, octene-2, nonene-3,nonene-2, nonene-4, benzene, toluene, o-xylene, m-xylene, p-xylene andpseudocumene, etc. It is understood that the aforementioned olefinseparation products and the original mixtures are only representative ofthe class of compounds which may be employed and that the presentinvention is not necessarily limited thereto.

Another variable which is employed in the separation process is thethiol resin utilized to effect the separation. The thiol resin comprisesa vinyl thiophenol, a thioaryl acrylate or an unsaturated thio acid anda divinylbenzenestyrene or divinylbenzene-methyl methacrylate copolymer.Some suitable examples of thiol resins which may be utilized includevinyl thiophenol-divinylbenzene-styrene copolymer, thio-methacrylicacid-divinylbenzene-methyl methacrylate copolymer, thio-methacrylicacid-divinylbenzene-styrene copolymer, thiopentacrylicacid-divinylbenzene-styrene copolymer, thio-hexacrylicacid-divinylbenzene-methyl methacrylate copolymer, p-thiophenylacrylate-divinylbenzene-styrene copolymer, p-thiophenyl methacrylatedivinylbenzene styrene copolymer, p-thiotolylethacrylate-divinylbenzene-styrene copolymer, etc. It is understood thatthe aforementioned thiol resins are only representative of the class ofthiol resins which may be employed and that the present invention is notnecessarily limited thereto.

The process of this invention may be effected in any suitable manner andmay comprise either a batch or continuous type of operation. Forexample, when a batch type operation is employed, the mixture ofparafiinic, olefinic and aromatic compounds is placed in an appropriatevessel which would include a flask if the reaction is to be effected atambient pressure or a pressure-resistant vessel such as an autoclave ifsuper-atmospheric pressures are to be employed containing the thiolresin. After maintaining the vessel at a predetermined temperature, itis drained of all constituents, refilled with a hydrocarbon, rotatedvigorously and redrained of all constituents. At this point the vesselis heated to a predetermined temperature while the gaseous or liquidphase egressing from the resin is trapped a the pure olefin desired.Where the hydrocarbon purge remains as an impurity in the olefinproduct, a distillation may be necessary to purify the olefin.Alternatively, if superatmospheric pressures are to be employed in theseparation, the parafiinic, olefinic and aromatic mixture is charged toan autoclave containing the thiol resin while substantially inert gassuch as nitrogen is pressed in until the desired operating pressure isreached. The autoclave is then heated to effect the separation for apredetermined period of time at which point heating is discontinued andthe autoclave is purged, heated and the desired olefin is recovered asheretofore mentioned when operating at ambient pressure. Suitableexamples of hydrocarbons which may be used in the separation process toflush the resin bed after the formation of the thio-ethers includemethane, ethane, propane, butane, pentane, hexane, heptane, octane,decane, undecane, pentadecane, eicosane, benzene, toluene, 0- xylene,m-xylene, p-xylene, cumene, ethylbenzene, 1,2- diethylbenzene, l,2,3,4,5pentamethylbenzene, pseudocumene, hexamethylbenzene, etc. the choicebeing such as to provide a flushing material which is non-reactive withthe thiolic copolymer and easily separable from the recovered olefin.The procedure is utilized to insure that all hydrocarbons have beenremoved from the resin except those retained as thio-ethers and thoseutilized as the purging agents.

It is also contemplated within the scope of this invention that thereaction process for obtaining the olefin may be effected in acontinuous manner of operation. When such a type of operation isemployed, the paraffinic, olefinic and aromatic mixture or a mixture ofuand internal olefins is continuously charged to a reaction zone whichcontains a bed of granular thiol resin, said zone being maintained atthe proper operating conditions of temperature and pressure. The liquidhourly space velocity is determined by the temperature and differencesin rates of forming the thio-ethers between the various components ofthe mixture, and is maintained thereat by a constant monitoring of theamount of mixture charged per hour into the separation zone. Aftercompletion of the desired residence time as controlled by the liquidhourly space velocity, the resin bed, after purging of the unreactedfeed components, is heated, generally to a temperature in the range ofabout to about 300 C., thereby decomposing the thio-ether to the thiolresin and the desired olefin. The thiol resin i thereafter re-utilizedas the separating agent. The remaining mixture which has not beenretained by the formation of the thio-ethers is recovered as theraffinate stream from the reactor vessel.

Another type of continuous operation which may be employed comprise theslurry type process in which the paraffinic, olefinic and aromaticmixture is passed through the reaction zone in a slurry with the thiolresin in finely divided form, the thio-ether compounds are withdrawn asthe reactor eflluent and heated to reform the separated olefin and thiolresin, which can be recharged to the slurry as a separating agent.

The following examples are given to illustrate the process of thepresent invention which, however, are not intended to limit thegenerally broad scope of the present invention in strict accordancetherewith.

EXAMPLE I In this example a mixture of butene-2, propane and butane witha trace of air are added to an autoclave containing a vinylthiophenol-divinylbenzene-styrene copolymer. The autoclave is maintainedat a temperature of 50 C. and a pressure of 15 atmospheres for 1 hour atwhich time the pressure is released and the residual gases vented. Theresin in the autoclave is heated to 180 C. while the egressing gas isrecovered and analyzed by means of gas chromatography, said analysisestablishing the gas to consist of a mixture of butenes high inbutene-2. Further analysis performed on the remaining mixture indicatedthat the mixture after treatment with the vinyl-thiophenol resin issubstantially butene-Z free. The resin is recovered from the autoclaveafter heating and analyzed by means of infra-red, said analysisdiscloses the resin is substantially that of the vinylthiophenol-divinylbenzene-styrene copolymer used to initiate theseparation.

EXAMPLE II In his example a moving resin bed of p-thiophenylmethacrylate-divinylbenzene-styrene copolymer is utilized while amixture of pentene-Z, pentane, hexane, octane and benzene with traces ofair, is flushed through the resin at a liquid hourly space velocity of2.3. The separation zone is maintained at a temperature of 60 C. and apressure of atmospheres. The mixture which passes through thep-thiophenyl methacrylate resin is analyzed by means of gaschromatography; said analysis discloses a pentene-2 free mixture. Theresin recovered is heated to 185 C. and the gas egressing therefromrecovered and analyzed by means of gas chromatography, said analysisdiscloses a substantially high purity mixture of pentene-l andpentene-2. The thiol resin is analyzed by infra-red, and said analysisshows the resin possesses almost identical properties to that which isused to initiate the separation process.

'EXAMPLE IH In this example a moving resin bed of thio-methacrylicacid-divinylbenzene-methyl methacrylate polymer is utilized while amixture of pentene-l, pentane, pentene-Z and heptene-2 with a trace ofair, is charged to the separation zone at a rate of 3.2 liquid hourlyspace velocity. The separation zone is maintained at a temperature of 40C. and a pressure of 10 atmospheres. The mixture which passes throughthe thio-methacrylic acid resin is analyzed by means of gaschromatography; said analysis discloses a pentene-l free mixture. Theresin recovered is heated to 160 C. and the escaping gas recovered andanalyzed by means of gas chromatography, said analysis discloses amixture of pentene-l and penetene-2. The thiol resin is analyzed afterheating by infra-red, said analysis disclosed the resin possesses almostidentical properties with that which is utilized to initiate theseparation.

I claim as my invention:

1. A process for the separation of a mono-olefin from a mixture ofparafiinic, olefinic or aromatic compounds which comprises contactingsaid mixture with a thiol resin and reacting the olefin with the resin.heating the resulting reaction product to a temperature sufiicient todecompose the same to olefin and thiol resin, and recovering the thusliberated olefin.

2. The process of Claim 1 further characterized in that the olefin-resinreaction conditions include a temperature of about 25 C. to about 150 C.and a pressure of from about atmospheric to about atmospheres.

3. The process of Claim 1 further characterized in that the olefin-resinreaction conditions include a liquid hourly space velocity from about0.1 to about 25.

4.. The process of Claim 1 further characterized in that the mixturecontains butene-Z, propane and butane and the recovered olefin comprisesn-butenes.

5. The process of Claim 1 further characterized in that the mixturecontains pentene-Z, pentane, heptane, octane and benzene and therecovered olefin comprises n-pentene.

6. The process of Claim 1 further characterized in that the mixturecontains pentene-I, pentane, pentene-Z and heptene-2 and the separatedolefin is pentene-l.

7. The process of Claim 1 further characterized in that the thiol resinis a vinyl thiophenyl-divinylbenzene-styrene copolymer.

8. The process of Claim 1 further characterized in that the thiol resinis thioaryl acrylate-divinylbenzenestyrene copolymer.

9. The process of Claim 1 further characterized in that the thiol resinis a thio-methacrylic acid-divinylbenzenemethyl methacrylate copolymer.

References Cited UNITED STATES PATENTS 3,121,124 2/1964 Verdol 2606773,629,478 12/ 1971 Haunschild 260677 A 3,634,534 1/l972 Haunschild260-677 A 1,968,601 7/1934 Edlund et al 260677 A DELBERT E. GANTZ,Primary Examiner I. M. NELSON, Assistant Examiner U.S. Cl. X.R. 260--676R, 674 R

1. A PROCESS FOR THE SEPARATION OF A MONO-OLEFIN FROM A MIXTURE OFPARFFINIC, OLEFINIC OR AROMATIC COMPOUNDS WHICH COMPRISES CONTACTINGSAID MIXTURE WITH A THIOL RESIN AND REACTING THE OLEFIN WITH THE RESIN,HEATING THE RESULTING REACTION PRODUCT TO A TEMPERATURE SUFFICIENT TODECOMPOSE THE SAME TO OLEFIN AND THIOL RESIN, AND RECOVERRIN THE THUSLIBERATED OLEFIN.